1. Field of the Invention
This invention relates to an optical link module, by which an optical signal is transmitted and/or received.
2. Related Prior Art
An optical link module has an optical transmitting sub-assembly (TOSA) that converts an electrical signal to an optical signal, and an optical receiving sub-assembly (ROSA) that converts the optical signal to the electrical signal. These TOSA and ROSA are enclosed within a housing so as connected to a wiring substrate. Such optical link module has been disclosed in the U.S. Pat. No. 6,074,228.
The TOSA, the ROSA and the wiring substrate are arranged and fixed within the housing. In the link module with a pluggable function, the accurate position of the wiring substrate is required to connect the board with external terminals. When the wiring substrate is rigidly fixed within the housing to secure the positional accuracy, a residual stress due to a difference of the thermal expansion coefficient of assemblies is accumulated in the portion where the TOSA and the ROSA are fixed to the wiring substrate, which causes a deformation and a deterioration of a reliability of the module.